textproduct: Rapid City

KEY MESSAGES

- Some patchy fog may linger along the foothills through Saturday morning.

- Remaining dry and unseasonably mild through the weekend and into next week.

DISCUSSION

(This Evening Through Friday) Issued at 123 PM MST Fri Jan 2 2026

Latest analysis shows 500hpa wave dropping southeast through NE currently with wintry mix occurring south of the FA with western CONUS ridge having retreated westward slightly over the past 24 hours. Northwest flow remains entrenched over the region with next wave to impact the region now crashing onshore onto the northern CA/OR coast. At the surface, the baroclinic boundary has sagged southwest of our SD counties, with most places now struggling in the mid 20s for temps with the exception of the Black Hills and our WY counties who are enjoying mid to upper 40s by being above the inversion layer or on the warm side of the boundary.

Weak WAA begins aft 00Z Saturday across the FA, but questions remain on how much will actually work down to the surface based on weak surface winds keeping mixing at bay. Hi-res models do show sfc winds becoming light westerly as frontal boundary begins to push back to the east as a warm front during the overnight hours. Am a bit worried about patchy fog lingering along the foothills of the Black Hills through the morning hours which will affect sensible temps. Right now, NBM solution has temps slowly rising through the night with boundary pushing back to the east and westerly sfc winds. Latest visible satellite pix do show some clearing in the clouds with the subsidence behind the exiting wave, so perhaps it will be enough to keep any patchy fog at bay.

Otherwise western CONUS ridge strengthens and pushes east over the region through the weekend. Fairly vigorous 700hpa wave moves through the upper midwest during the morning hours on Sunday, flattening the ridge. This drags a surface trough through the region with good westerly surface winds expected. There are some minor chances for some higher elevation pcpn as this surface feature passes, but not enough confidence right now to include in the forecast. Sunday still appears to be the warmest day heading into the next week. Another wave moves through the developing upper zonal flow Monday night, bringing some small chances for pcpn to the hills and parts of the plains.

Upper flow remains zonal through mid-week before turning southwest with falling 500hpa heights ahead of the digging west coast trough. This will usher in falling 850hpa temps and increasing chances for pcpn toward the end of next week.

AVIATION

(For the 00Z TAFS Through 00Z Saturday Evening) Issued At 345 PM MST Fri Jan 2 2026

MVFR/IFR/LCL LIFR conditiions in low stratus and freezing fog around the foothills and adjacent plains will slowly improve to VFR through this evening. Patchy fog may redevelop over northwestern into south central SD late tonight into early tomorrow morning but MVFR/IFR conditions not expected to reach the foothills or affect the KRAP terminal. Expect VFR conditions to prevail across NE WY, across the Black Hills and SW SD through the valid TAF period.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.